This invention pertains to controlled variable time fuzes and more specifically to the improvement of military controlled variable time fuzes by synchronizing arming of point detonation apparatus with arming of controlled variable time detonation apparatus. Certain fuzes in use with military weapon systems for detonating an explosively loaded projectile are designed so that they can be set by the firing crew to function exclusively on impact with a target, referred to as point detonation (PD), or on proximity to the target, referred to as controlled variable time detonation (CVTD). At the latter setting, the PD feature is active as a back-up to the CVTD feature.
When these prior art fuzes are set to operate in the CVTD mode, the time after launching at which the CVTD circuit arms is selected to obtain various tactical advantages such as safe operation when in proximity to friendly terrain. When so set, the PD circuit arms almost immediately after launching. So detonation will occur upon accidental impact with friendly terrain.
The present invention, however, provides that when the fuze is set to function in the CVTD mode, PD arming is withheld until the time selected for CVTD arming. The advantage of this arrangement is that the projectile cannot detonate, by normal fuzing action, upon accidental impact occuring before the selected time after launch. The present invention further does not preclude the fuze from being set exclusively in the PD mode.